Table 6.

Vaccine Effectiveness in the Influenza-Active Season

Influenza Virus Subtype	No.	Odds Ratio (95% CI)	VE, % (95% CI)a
2011–2012
All influenza subtypes	122	0.268 (.097–.738)	73 (26 to –90)
Only influenza virus type A(H3N2)	121	0.288 (.103–.806)	71 (19 to –90)
2012–2013
All influenza subtypes	206	0.493 (.262–.928)	51 (7–74)
Only influenza virus type A	178	0.423 (.211–.850)	58 (15–79)
Only influenza virus type A(H3N2)	154	0.330 (.137–.796)	67 (20–86)
Only influenza virus type A(H1N1)pdm09	137	0.466 (.179–1.215)	53 (–22 to 82)
Only influenza virus type B	141	0.570 (.203–1.600)	43 (–60 to 80)
Only influenza virus type B/Yamagata	136	0.935 (.286–3.056)	7 (–205 to 71)

For more details, see Supplementary Table 3.

Abbreviations: CI, confidence interval; VE, vaccine effectiveness.

^aCorrected for the possible confounders age group, comorbidity, sex, and smoking. Data were calculated for the influenza-active period in the Netherlands as defined by the Netherlands Institute for Health Services Research [11].